(a) Field of the Invention
The invention pertains to the field of database management and, more particularly, to a method and apparatus for providing critical time reactive management of database transactions for a systems process such as a Mission Critical Computer System.
(b) Description of the Related Art
Traditional approaches to providing information management for a Mission Critical Computer System (MCCS) have been to provide ad hoc solutions which are tailored to a specific situation. Such implementations are hand crafted to each problem and provide a minimal level of versatility.
Conventional memory management approaches and database approaches both have shortcomings for applications such as MCCS. For example, conventional memory management approaches provide timely and prioritized access to information, but are not sufficiently accurate, secure and consistent when used in conjunction with powerful access methods which are needed in real-time applications such as MCCS. Database approaches, while providing accurate, secure and consistent access to information, do not provide the necessary prioritized access to this information.
For example, U.S. Pat. No. 4,961,139, to Hong et al., discloses a database management system for real-time applications which includes the option to "read-through-lock" to access data in locked data tables. Searching speed is improved through the use of "tuple" identifiers. However, data calls are still handled on a "first in first out" basis. Thus, calls which may be critical to the application must wait for the completion of all prior calls before they can be processed.
U.S. Pat. No. 4,881,166, to Thompson et al., discloses a method for consistent multidatabase transaction processing for permitting the correct execution of multiple concurrent transactions, each comprising one or more read and/or write operations, in a heterogeneous distributed database system. This system, however, also processes transactions on a "first in first out" basis which is not acceptable in critical time applications.
U.S. Pat. No. 5,006,978, to Neches, discloses a relational database system having a network for transmitting colliding packets and a plurality of processors each storing a disjoint portion of a database. Priority determining nodes are used to provide prioritized processing of messages, thus improving critical time performance. However, consistency between concurrently executing messages is not ensured.
It is, accordingly, the principal object of the present invention to provide a real time database management system which can process transactions in a concurrent and prioritized fashion, while maintaining the accuracy, security and consistency of database methods.
It is a further object of the present invention to provide such a database management system which is flexible and versatile and, therefore, useful for numerous applications.
Further objects and advantages of the present invention will be apparent to those skilled in the art after a consideration of the following disclosure of the invention.